A number of factors contributed to the recent flooding at the Wastewater Treatment Plant on Saturday, January 23, 2021. The primary cause of the 2016 flood was a power failure due to lightning strike, which was not the cause this time. Many of the systems implemented after the 2016 flood did work correctly, including the generator system, independent automatic gate valve system, and the “dead-man” alarm.
One major safeguard against flooding events is an independent automatic gate system. The independent automatic gate system, where wastewater initially enters the treatment facility, did close automatically when the power was lost and prevented untreated water from entering. The recirculated water was the source of flooding because we did not have the same gate system for our recirculation line. The recirculation line takes water from the aeration ponds and brings it back into the plant for a second cleaning, which helps keep our treatment bacteria healthy. We anticipate installing an independent automatic gate system for our recirculation line due to the increased use of this line after upgrading the aeration system.
In regards to our electrical system, our generator was in good shape. The generator was purchased in 2016 and automatically tests itself every Tuesday. This cycles the fuel and keeps the generator in good working order. However, for an unknown reason, the main breaker tripped and the generator’s electricity was not able to flow into the system. Our engineers and electricians are working to solve this problem to prevent this specific issue in the future.
Our alarm system has two components. The most critical alarm, the “dead-man” alarm, did sound. This alarm indicates that there is a major failure and immediate action is required. This alarm was cleared by staff remotely, without taking the appropriate actions. This system is being modified so that the alarm cannot be cleared remotely. For any alarm in our entire system to be cleared in the future, a staff member will be required to go on-site.
We also have an initial alarm system, known as “high water” alarms. These four alarms are placed on the floor of the treatment plant and in the wastewater intake channel. These alarms sound as soon as water triggers them. Although these have sounded in all routine testing, they did not go off this time despite battery back-up. The electricians are evaluating this issue and will make recommendations based on their findings.
Our final major change to the alarm system is that we will expand the alarm system into the compressor building. This will protect it from any potential flooding and generator failures. It will be connected to a limited-power backup battery. We will also be adding a power outage alarm and a tripped breaker alarm.
The wastewater treatment plant also had several standard operating procedures and double-checks which will be upgraded and clarified. These are being thoroughly reviewed by engineers, SCADA, and staff to guarantee that they are comprehensive. We are also implementing more thorough documentation of tracking procedures to guarantee that these are being followed appropriately.
We are investing in more in-depth training for staff, including SCADA and internal controls and safeguards. All of these changes will also be implemented at both the Wastewater Treatment Plant and the Water Treatment Plant. The anticipated modifications to our systems are subject to appropriation. We do not have a cost estimate at this time, although we do know that the generator will not need to be replaced. All matters of personnel are confidential and cannot be released. However, we have thoroughly investigated the incident and have taken all appropriate actions.
For more information, please contact Mira Miller, City of Rawlins Community Relations Coordinator, at 307-328-4500 ext. 1022.
